On 02/19/2016 09:41 AM, Arnd Bergmann wrote: > On Thursday 18 February 2016 14:46:14 Murali Karicheri wrote: >> From: Arnd Bergmann <[email protected]> >> >> The commit 899077791403 ("netcp: try to reduce type confusion in >> descriptors") introduces a regression in Kernel 4.5-rc1 and it breaks >> get/set_pad_info() functionality. >> >> The TI NETCP driver uses pad0 and pad1 fields of knav_dma_desc to >> store DMA/MEM buffer pointer and buffer size respectively. And in both >> cases for Keystone 2 the pointer type size is 32 bit regardless of >> LAPE enabled or not, because CONFIG_ARCH_DMA_ADDR_T_64BIT originally >> is not expected to be defined. >> >> !LAPE LPAE >> sizeof(void*) 32bit 32bit >> sizeof(dma_addr_t) 32bit 32bit >> sizeof(phys_addr_t) 32bit 64bit > > As this was never relevant or true, I don't think it needs to be > mentioned here, it just confuses things. Please just assume that > dma_addr_t can be 64-bit wide, but will only contain 32-bit > numbers on keystone. > >> Unfortunately, above commit changed buffer's pointers save/restore >> code (get/set_pad_info()) and added intermediate conversation to u64 >> which works incorrectly on 32bit Keystone 2 and causes TI NETCP driver >> crash in RX/TX path due to "Unable to handle kernel NULL pointer" >> exception. This issue was reported and discussed in [1]. > > Have you been able to figure out why it actually broke? I'd still > like to know. > I have just send v2. I will investigate your original patch that added regression this afternoon and respond with my observation as soon as my investigation is complete. I assume, you are trying to make the change such that the virtual pointers stored in sw_data/pad works across 32bit and 64bit machine, right?
Murali >> Hence, fix it by partially reverting above commit and restoring >> get/set_pad_info() functionality as it was before. >> >> [1] https://www.mail-archive.com/[email protected]/msg95361.html >> Cc: Wingman Kwok <[email protected]> >> Cc: Mugunthan V N <[email protected]> >> CC: David Laight <[email protected]> >> Reported-by: Franklin S Cooper Jr <[email protected]> >> Signed-off-by: Arnd Bergmann <[email protected]> >> Signed-off-by: Grygorii Strashko <[email protected]> >> Signed-off-by: Murali Karicheri <[email protected]> > > I don't think I sent this patch with a 'Signed-off-by', did I? > (I could be misremembering that). > > Arnd > -- Murali Karicheri Linux Kernel, Keystone
